Field of the Disclosure
Embodiments of the present disclosure generally relate to rig equipment. More specifically, embodiments of the disclosure relate to a mobile jackup oil rig having a crane, as well as to mobile jackup rigs used for other purposes, such as accommodations, platform decommissioning work, etc.
Description of the Related Art
Offshore marine oil exploration and drilling is often undertaken from mobile offshore drilling units, the type of mobile offshore drilling unit selected based on the drilling location water depth and remoteness from land. Jackup rigs are one such mobile offshore drilling unit, which commonly include a watertight barge or hull that floats on the water's surface until the jackup rig reaches the desired drilling location. Upon reaching the desired drilling location, three or more jacking towers of the jackup rig are jacked downward through slots or openings in the hull of the jackup rig, into the water, and into the sea floor to anchor the rig to the sea floor. With the rig anchored, the jackup rig can be raised above the water to accommodate anticipated changes in sea level height, such that waves, tides, and currents do not cause undesirable changes in the location and orientation of the barge, platform, or drilling package.
The jackup rig and its deck have limitations with respect to the amount of available space and weight capacity. Drilling equipment, supplies, living quarters, and other essentials required on the platform deck, or floor, during drilling operations must be moved, stored, and/or located on the jackup rig deck platform, all of which affect the size of the jackup rig. Within the oil and gas industry there is a drive to lower the cost of oil rigs and platforms.
Current jackup rigs maintain three or more fixed pedestal cranes on their deck platforms in order to service all areas of the jackup rig, the jackup rig deck platform, and areas adjacent the jackup rig. Each pedestal crane is secured in its location such that it cannot move about the jackup rig deck platform, but can only rotate about the longitudinal axis of the pedestal. Maintaining three or four pedestal cranes per jackup rig significantly increases the weight of the overall jackup rig, and decreases the amount of useable space on the jackup rig. Less usable deck space results in less equipment that may be carried on the jackup rig deck, a reduction in the number of personnel able to be supported by the rig, a greater frequency of supply boat dockings to receive, or trade out, supplies, equipment, and personnel, a reduction in workspace, and a reduction in the types of materials that may be brought onto the jackup rig. Furthermore, the requirement of three or more pedestal cranes on a jackup rig increases the cost to build, operate, and maintain the jackup rig. More pedestal cranes require more maintenance, spare parts, technicians, and operators, further using up jackup rig space.
Therefore, there is a need for a reduction in the weight and amount of equipment required to fully operate a jackup rig during oil exploration, drilling operations, or other rig operations, or to enable additional equipment to be carried thereon.